Dear All,
After a bit of further discussion, the following has become clear. Apparently, the number which you specify in the thermostats is the inverse relaxation time, which is mass dependent. So if you want to get the same friction coefficient, you'll need to take the mass into account. After browsing through the User's Guide some more, I'm pretty sure that this is not the behavior ESPResSo advertises. Moreover, I am fairly certain that there are now inconsistencies in the code, because some features (a.o. ENGINE) have based their mass dependence on the idea that the "friction" is a proper friction, not an "inverse relaxation time", to make sure that there is no odd mass dependency. Pretty much a fail all round. I'll open a bug report on it.
Kind Regards,